SPID#: 65 This project has multiple aims to describe development in chimpanzees in comparison to humans; to compare development in chimpanzees raised under different rearing conditions; to better understand developmental processes through the cross-species comparison of rates of development across systems (e.g., perceptual, motor, emotional, and cognitive). Humans and chimpanzees differ in developmental rates within the cognitive and motoric systems. They do not appear to differ in developmental rates within visual system. We are still investigating comparative development within the social, and emotional systems. With regard to parenting, it appears that certain developmental experiences are crucial. Due to a lack of experience in handling infants, there are some adult female chimpanzees without adequate maternal behaviors to raise their infants. To insure infant survival, these infants are raised in the Great Ape Nursery (GAN). The GAN has utilized two types of rearing in the last 10 years, Standard Care (ST) and Responsive Care (RC). ST was designed to maximize species-typical development primarily through conspecific peer interactions. RC was designed to more closely approximate species- typical rearing by training adult human caregivers to interact with infants using chimpanzee species-typical behaviors based on competent chimpanzee mothers. Normative data have been collected on infants raised under these two nursery settings and compared with data collected from mother-reared infants. Analyses indicate that the neurobehavioral integrity of infants, 2 to 30 days of age, differs somewhat RC are more alert but ST are more capable of self-regulating. RC infants were more like mother-reared infants, exhibiting a less well developed ability to self-quiet and regulate their state compared with ST. Meaningful differences were found in emotional expressiveness from 3 to 12 months of age. Chimpanzees given RC were significantly more positive in their emotional responsiveness on standardized tests of cognitive and manipulative performance compared with chimpanzees given ST. Rearing environment can alter the temperament of chimpanzees. The comparison of development across species with consideration of the differences in coordination between systems can broaden our understanding of necessary and sufficient conditions which may underlie development. For example, chimpanzees compared with humans infants are more advanced in motoric ability but similar in the development of attachment and wariness of strangers. Thus, locomotor ability can not be the necessary condition for the development of wariness of strangers these events co-occur in human infants but there is substantial lag in chimpanzee infants. Cross- species comparisons, developmentally focused, are invaluable to disentangle those processes that are confounded in human development.